package middleware

import (
	"net/http"

	"github.com/gin-gonic/gin"
)

// 跨域
func Cors() gin.HandlerFunc {
	return func(c *gin.Context) {
		method := c.Request.Method               // 请求方法
		origin := c.Request.Header.Get("Origin") // 请求头部
		if origin != "" {
			c.Writer.Header().Set("Access-Control-Allow-Origin", "*")
			c.Header("Access-Control-Allow-Origin", "*")
			// 这是允许访问所有域
			c.Header("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE, UPDATE")
			// 服务器支持的所有跨域请求的方法,为了避免浏览次请求的多次'预检'请求
			// header的类型
			c.Header("Access-Control-Allow-Headers", "Authorization, Content-Length, X-CSRF-Token, Token,"+
				"session,X_Requested_With,Accept, Origin, Host, Connection, Accept-Encoding, Accept-Language,DNT, "+
				"X-CustomHeader, Keep-Alive, User-Agent, X-Requested-With, If-Modified-Since, Cache-Control, "+
				"Content-Type, Pragma")
			// 允许跨域设置
			// 可以返回其他子段
			c.Header("Access-Control-Expose-Headers", "Content-Length, Access-Control-Allow-Origin, "+
				"Access-Control-Allow-Headers,Cache-Control,Content-Language,Content-Type,Expires,Last-Modified,Pragma,FooBar")
			// 跨域关键设置 让浏览器可以解析
			c.Header("Access-Control-Max-Age", "172800")
			// 缓存请求信息 单位为秒
			c.Header("Access-Control-Allow-Credentials", "false")
			// 跨域请求是否需要带cookie信息 默认设置为true
			c.Set("content-type", "application/json")
			// 设置返回格式是json
		}
		// 放行所有OPTIONS方法
		if method == "OPTIONS" {
			c.AbortWithStatus(http.StatusNoContent)
		}
		// 继续处理请求
		c.Next()
	}
}
